Former FBI Director Robert Mueller, the special counsel probing Russian interference in the 2016 election, departs Capitol Hill following a closed door meeting in Washington

Speculation is running rampant within the Beltway that over the holiday break President Donald Trump might try to oust Special Counsel Robert Mueller, who is leading the expansive investigation into whether the Trump presidential campaign colluded with Russia. Trump continues to publicly deny the rumors, insisting he won’t fire Mueller.

Meanwhile, even as someRepublican Party officials have been fomenting opposition to Mueller to build support for Trump dumping him, progressive organizations and Democratic leaders alike have called for immediate protests in the streets should Trump actually fire the special prosecutor. This has all created a sense of heightened drama to close out a year that has had no shortage of it.

It’s important to note, however, that many legal experts strongly contend that the president himself does not have the authority to fire Mueller. That authority lies solely with the United States Attorney General (or in this case the deputy, because Jeff Sessions has recused himself from this investigation), and even then Department of Justice regulations require that there be good cause. Deputy Attorney General Rod Rosenstein recently testified before Congress that he has no intention of firing Mueller.

Of course, Trump might make a play to push out Rosenstein—whose recent testimony Trump reportedly mocked as “weak”—and find someone in the Justice Department who is willing get rid of Mueller (just as Richard Nixon did when he dismissed his attorney general and deputy attorney general before he found a ranking Justice official—Solicitor General Robert Bork—willing to fire special prosecutor Archibald Cox).

So what happens to Mueller’s expansive investigation if he is fired? The answer is complicated. Notwithstanding the inevitable political backlash and legal challenges, the federal investigation into potential collusion between the Trump campaign and Russia does not depend on Mueller.

“The DOJ investigation doesn’t go away if Mueller is fired,” says Noah Bookbinder, executive director for Citizens for Responsibility and Ethics in Washington. “The investigation would continue, whether under some new special counsel or under the regular power structure of DOJ.”

It’s not so easy to close down an open federal investigation either, as there is a process by which federal investigations are closed, including a detailed report providing a legal rationale for ending it. “That process would take some time,” American Constitution Society President Caroline Fredrickson says. “And it would bring such attention to the case that it would not be a terribly advantageous route for the president to follow.”

Fredrickson says she’s much more worried about other efforts by the administration to obstruct justice, whether it’s by appointing someone above Mueller, underfunding the investigation, constructing bureaucratic hurdles that make it harder for investigators to get what they need, or undermining Mueller’s credibility through political attacks. “Those are more dangerous,” she says. “I think Mueller at this point is protected.”

That’s in part because Mueller has created numerous safeguards and safety valves to protect the investigation—even if he is eventually shown the door. His most important safeguard could be his ability to loop state prosecutors into various parts of the investigation. There are ways he could do that—and ways he can’t. “If Mueller is fired, he won’t have any ability to turn over documents he once had possession of,” Jed Shugerman, a Fordham University law professor who has written extensively about the Mueller investigation, told the Prospect.

The solution, Shugerman says, is something that Mueller has probably already done: share information with state prosecutors. “This is very common in organized crime investigations where you have multiple states involved and they have to coordinate,” Shugerman explains. “There are different witnesses and they have to figure out who has best chance of getting the best charge.”

Indeed, news broke in late August that Mueller was working closely with New York Attorney General Eric Schneiderman on the investigation into former Trump campaign chairman Paul Manafort and his financial dealings. Shugerman believes it’s highly likely that there are several other fronts that Mueller is working in tandem with Schneiderman (who is the attorney general of Trump’s home state, of course) and, perhaps, other state attorneys general on.

After Mueller formally brought charges against Manafort and George Papadopoulos, some observers wondered why they were so limited—and didn’t include more serious charges for tax fraud or money laundering. That may be Mueller’s insurance policy in case Trump decides to pardon certain figures as a way to prevent higher-profile individuals from flipping. By leaving certain charges off his own bill of particulars, they are still available to state prosecutors without double jeopardy worries.

Shugerman argues that states—particularly New York—can prosecute implicated Trump associates on a whole host of different crimes, including tax fraud, money laundering, conspiracy in computer hacking, and obstruction of justice.

The New York statute does not allow a state prosecution to follow a federal prosecution … for the same basic facts. The bottom line: If Mueller starts a trial on all of the potential charges, and then Trump pardons Manafort, Mueller will not be able to hand off the case to state prosecutors. And thus he would have lost leverage at the time of the indictment if he seemed headed toward losing the state prosecution as a backup.

Instead, Mueller wisely brought one set of charges (mostly financial crimes that preceded the campaign), and he is saving other charges that New York could also bring (tax fraud, soliciting stolen goods, soliciting/conspiring to hack computers). Mueller also knew that his indictment document … would include a devastating amount of detail on paper without relying on any witnesses to testify, showing Mueller had the goods on a slam-dunk federal money laundering case. Then he dropped the hammer with the Papadopoulos plea agreement, showing Manafort and Gates that he has the goods on far more charges, both in federal and state court.

It remains to be seen how Trump reacts as Mueller’s investigation circles in on the White House. But if Mueller plays his cards right—and many legal observers think he’s playing them masterfully—Trump will probably be unable to impede the investigation even if he fires the special counsel.